Genunsai (also spelled Gen'unsai) is the twin brother of Genryusai and grandfather of Kappei, residing in Iga of Oedo. While sharing physical similarities with his twin, Genunsai possesses distinct features: two noticeable bottom teeth and wild, unkempt hair, contrasting with Genryusai's typically covered hair; he does not wear a hat. His personality is markedly more energetic and expressive than his brother's reserved demeanor. As Kappei's guardian, he sends Kappei to Komerica for training under Genryusai, partly to protect Gumchi, the gum-like alien sharing a close bond with Kappei. This action facilitates Kappei's involvement with the World Ninja Association. Genunsai appears in the 2D Cartoon Anime adaptation, where his animated expressions include moments of being startled or yelling.